Cardinals quarterback Carson Palmer announced his retirement from the NFL at the end of December, ending his 15-season career. Palmer made the announcement in an open letter issued by the Cardinals. He missed nine of his final season’s games due to a broken arm. He leaves as the only quarterback to throw more than 4,000 yards in a season with three teams: twice for Cincinnati, once for Oakland, and once for Arizona.

Palmer entered the league when he was 23 years old. He won the Heisman Trophy at the University of Southern California in 2002, and was the No. 1-overall pick by Cincinnati in the same year. Palmer also threw 46,247 yards, the 12th-most in NFL history. He suffered from torn ACL injuries twice in his career: The first time in Cincinnati in 2005, when he was hurt on his first pass during a 66-yard completion, and the second time in the sixth game of the 2014 season. In 2015, he set a record for passes exceeding 4,671 yards and another for his 35 touchdowns, while also leading the Cardinals to victory with a 13-3 record, which is the second-best in the NFC. In that season, Palmer won his only playoff game in four tries in overtime over Green Bay.

Palmer left the Cincinnati Bengals after seven years when he got into a dispute with the owner, Mike Brown. In 2011, he was traded to the Oakland Raiders and was compensated with a first-round draft pick in 2012 and a second-rounder in 2013. After starting nine games with minimal success in wins and losses, Oakland deemed him invaluable and transferred him to the Arizona Cardinals.

Despite two torn ACL injuries, a broken arm, an elbow injury, a concussion, and shoulder injury, Palmer embarks on the next phase of his life saying that his career has and will always be “the most incredible experience of my life.” He leaves with his wife, four kids, and 15 years worth of experience.